The invention relates to an electric cable connection terminal where a core wire made of aluminum or aluminum alloy and a core wire consisting of copper or copper alloy are connected in a non-contact manner, introduced water is subject to waterproofing and thus corrosions of the core wire made of aluminum or aluminum alloy and the core wire consisting of copper or copper alloy are prevented, and a wire harness having the electric cable connection terminal.
In an automobile and the like, a variety of electronic devices are mounted. Hence, in the automobile and the like, a wire harness is arranged so as to deliver desired power or signal to the electronic devices. The wire harness has an electric cable having a terminal fitting for connection to the electronic device compression-connected to a terminal thereof. For the terminal fitting, copper or copper alloy that has the performance and reliability over a long time period and has been thus stably used is generally used.
In recent years, in order to save the energy or to reduce the exhaust gas, the electric cable of the wire harness that is arranged in the automobile and the like has been changed from an electric cable having a conductor made of copper or copper alloy to an electric cable having a conductor made of aluminum or aluminum alloy.
However, the aluminum or aluminum alloy forms a robust oxide film on a surface thereof. Thus, when a terminal fitting made of copper or copper alloy is compression-connected to a terminal of an electric cable having a conductor made of aluminum or aluminum alloy, contact resistances of the conductor and the terminal are increased with time. Therefore, it is difficult to perform the compression connection having the high reliability with the same manner as that for the electric cable having a conductor made of copper or copper alloy.
Also, the connection reliability of the terminal fitting made of copper or copper alloy is secured by an extensive performance evaluation including a durability test at a development stage or by an actual longtime using performance in a vehicle. Therefore, when the terminal fitting is made of aluminum or aluminum alloy, the compression conditions should be optimized, the connection reliability should be confirmed and the terminal should be developed, so that much cost and time are required.
Accordingly, a terminal connection structure has been suggested in which an electric cable having a conductor made of aluminum or aluminum alloy is connected with an electric cable having a terminal fitting made of copper or copper alloy and provided at a terminal and having a conductor made of copper or copper alloy (for example, refer to Patent Document 1). According to the terminal connection structure of Patent Document 1 (JP-A-2009-9736), an electric cable having a core wire made of aluminum or aluminum alloy is connected with an electric cable having a terminal fitting made of copper or copper alloy and provided at a terminal and having a core wire made of copper or copper alloy, and an insulator tube is provided to the connection part.
Patent Document 1: JP-A-2009-009736
However, according to the terminal connection structure disclosed in Patent Document 1, the core wire made of aluminum or aluminum alloy is directly connected with the core wire made of copper or copper alloy and the connection part having connected the core wire made of aluminum or aluminum alloy and the core wire made of copper or copper alloy is simply covered with the insulator tube. Therefore, when water is introduced into the connection part by a capillary phenomenon, the connection part in which the different metals are connected and contacted to each other forms a local cell, so that contact corrosion of different metals, in which the aluminum is eluted as a cation, is caused. As a result, the contact resistance of the connection part is increased.